Why are Mn2+compounds more stable than F | Class 12 Chemistry Chapter The d-and f-Block Elements, The d-and f-Block Elements NCERT Solutions

Question:

Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4

Answer:

Molecules are made up of atoms & are  quite small, therefore the actual mass of a molecule cannot be detrmined.It is expressed as the relative mass.C-12 isotope is used to express the relative molecular masses of substances.Thus  molecular mass of a substance may be defined as: the average relative mass of its molecule as compared to the mass of carbon atom taken as 12 amu.

(i) H2O:

The molecular mass of water, H2O

= (2 × Atomic mass of hydrogen) + (1 × Atomic mass of oxygen)

= [2(1.0084) + 1(16.00 u)]

= 2.016 u + 16.00 u

= 18.016

= 18.02 u

(ii) CO2:

The molecular mass of carbon dioxide, CO2

= (1 × Atomic mass of carbon) + (2 × Atomic mass of oxygen)

= [1(12.011 u) + 2 (16.00 u)]

= 12.011 u + 32.00 u

= 44.01 u

(iii) CH4:

The molecular mass of methane, CH4

= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)

= [1(12.011 u) + 4 (1.008 u)]

= 12.011 u + 4.032 u

= 16.043 u


Study Tips for Answering NCERT Questions:

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  • Read the question carefully and focus on the core concept being asked.
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Comments

  • seya
  • 2019-03-08 13:48:59

easy to understand


  • sudip das
  • 2019-03-07 13:24:32

your answers are great but i would like to suggest that you should give the answer in such a manner that we can scroll down because here at each step we have to click which is time consuming


  • Akrati
  • 2019-02-13 12:05:32

Question is different it is asking why mn+2 is more stable but your answer says that Fe is more stable


  • neha
  • 2018-12-16 19:04:58

Best


  • YASH
  • 2018-11-30 07:51:02

grt


  • Rohit soni
  • 2018-11-22 00:18:46

But in question fe+2 is more stable than MN+2,why,total chemistry is wrong.total exception👿


  • Omkar ojha
  • 2018-09-05 13:41:10

Best explain


  • Rohit kumar
  • 2018-04-27 16:59:46

Very useful, thanks


  • Deepak
  • 2018-04-16 23:08:10

Thanks


  • Alisha
  • 2018-03-11 12:08:25

Good answer helpful


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 2: Why are Mn2+compounds more stable than Fe2+ towards oxidation to their +3 state?....